This invention relates generally to a system and method for treating a patient and in particular to a system and method for controlling a treatment to administer a precise dose to a patient. In more detail, the invention relates to an apparatus and method for performing accurate surgical procedures on a particular target region within a patient utilizing previously obtained reference data indicating the position of the target region with respect to its surrounding which may contain certain reference points.
In order to control a surgical procedure, such as radiosurgery, many different prior techniques have been used including the manual targeting of the treatment. Many of the prior techniques are not sufficiently accurate so that healthy tissue surrounding the target region is often unnecessarily irradiated and damaged or killed. Other techniques are clumsy and cannot be used for particular types of treatments. For example, one prior technique involved frame-based stereotaxy that was often used for body parts and regions that could be easily physically immobilized. For example, the frame based stereotaxy was often used to immobilize the head of the patient so that a target region in the brain, such as a brain tumor, could be irradiated by the radiosurgical beam. To do so, the patient was positioned on a treatment bed and then his/her head was immobilized by a frame that was securely attached to the person""s head with some attachment means and that was also securely attached to an immovable object such as a treatment table. Thus, during the treatment, the patient was not able to move his/her head at all which permitted an accurate targeting of the treatment. The problem is that a frame-based system cannot be used for fractionated treatment in which repeated smaller dose are given to the patient over some predetermined period of time, such as a couple of weeks or a month. A fractionated treatment plan is often desirable since it permits larger overall doses of treatment, such as radiation, to be applied to the target region while still permitting the healthy tissue to heal. Clearly, it is extremely difficult to leave the frame secured to the patient""s head for that period of time. In addition, it is impossible to remove the frame and later reposition the frame in the exact same location for the next treatment. Thus, the frame based stereotaxy provides the desired accuracy, but cannot be used with various desirable treatment schedules.
Another typical positioning system is a frameless stereotaxy system wherein a physical frame attached to the patient is not necessary. An example of a frameless stereotaxy system is disclosed in U.S. Pat. No. 5,207,223 which is owned by the same assignee as the present invention and is incorporated herein by reference. In general, a preoperative imaging of the region surrounding the target region is completed, such as by computer tomography. Then, during the treatment, a stereo image is generated, such as by X-ray imaging. The stereo image is then correlated to the preoperative image in order to locate the target region accurately. Then, a radiation source located on a robot is automatically positioned based on the correlation between the preoperative scans and the stereo images in order to accurately treat the target region without unnecessarily damaging the healthy tissue surrounding the target region.
The current frameless stereotaxic techniques have some limitations which limit their effectiveness. First, most surgical operation rooms have limited workspace and the current stereotaxic frameless systems require a large space due to the movement of the robot supporting the surgical radiation beam and the two beam imagers. Second, the cost of having two beam generators and two imagers is very high making the treatment system very expensive. These systems also typically require some form of implanted fiducials, such as markers that are viewable using an X-ray, to track soft tissue targets. Finally, for most current frameless systems, breathing and other patient motion may interfere with the target region identification and tracking due to a degradation of the images. Thus, it is desirable to provide a frameless radiosurgery treatment system and method that overcomes the above limitations and problems and it is to this end that the present invention is directed.
A method and apparatus for selectively and accurately localizing and treating a target within a patient are provided. A three dimensional mapping of a region surrounding the target is coupled to a surgical intervention. Two or more diagnostic beams at a known non-zero angle to one another may pass through the mapping region to produce images of projections within the mapping region in order to accurately localize and treat the target.
To accomplish the accurate positioning and targeting, a three-dimensional (xe2x80x9c3-Dxe2x80x9d) mapping of the patient is generated for a portion of the patient""s body having the target region and stored as reference data. Then, two or more diagnostic beams are passed through the mapping region wherein the beams are at predetermined non-zero angle with respect to each other. A single image camera or recording medium may be used to capture the images from the one or more diagnostic beams such as shown in U.S. Pat. No. 5,207,223 to Adler. In more detail, the single image camera or recording medium may be segmented into one or more pieces so that the image from the first diagnostic beam is captured on a first piece of the recording medium, the image from the second diagnostic beam is captured on a second piece of the recording medium, the images are downloaded to a computer and then images from the subsequent diagnostic beams are captured.
Once the diagnostic images are generated, they are compared to the stored 3-D reference data to generate information about the patient and the location of the target region as is known from the Adler patent. At predetermined small time intervals, the diagnostic images are obtained and compared to the reference data. The results of the comparison may be used to adjust the targeting of the treatment beam on the target region to ensure that the dose of the surgical treatment beam remains focused on the target region. This results in a more accurate treatment so that fewer healthy cells and tissue are damaged by the treatment which results in fewer complications following the treatment and permits more aggressive and effective treatments.
In accordance with a first embodiment of the invention, there may be a diagnostic beam device or one or more diagnostic beam devices and a single recording medium underneath the patient or close to the patient couch. In one embodiment, the single diagnostic beam device moves in a predetermined manner to predetermined different positions so that the diagnostic beam, at each position, passes through the target region at predetermined angles. Thus, each image generated by the diagnostic beam device is at a predetermined non-zero angle with respect to the other images. Once the diagnostic images are generated, the above treatment control process is used.
In accordance with a preferred embodiment of the invention, a diagnostic beam device is used and a recording medium is located underneath the patient as described above. In this embodiment, the diagnostic images of the target region, formed by moving the diagnostic beam device, are gated with respect to real-time measurement of involuntary patient motion, such as respiration or pulsation. Thus, in this embodiment, the motion is compensated for as the treatment of the patient occurs and the images acquired by the diagnostic beams are not degraded by the movement of the target region.
The series of diagnostic beam images formed by the moving diagnostic beam generates a rough computer tomography (CT) scan of the patient that may be compared to the more precise pre-operative CT scan. In addition, the diagnostic beams and treatment beam may be energized and triggered during predetermined times during the respiration cycle of the patient to ensure accurate positioning of the target region.
Thus, in accordance with the invention, a system for directing a treatment beam towards a patient is provided. The system may comprise a treatment bed that supports the patient during the treatment and one or more diagnostic beam generators for generating diagnostic beams towards the patient during the treatment. The diagnostic beam generators may be located at different predetermined positions so that the beam from each diagnostic beam generator is at a predetermined non-zero angle with respect to the beams of the other diagnostic beam generators. The system may further comprise a single image recording device located adjacent to the treatment bed for receiving the diagnostic beams from the two or more diagnostic beam generators so that the image recording device captures the images from all of the diagnostic beams.
In accordance with another aspect of the invention, a system for directing a treatment beam towards a patient is provided that comprises a treatment bed that supports the patient during the treatment and a diagnostic beam generator for generating a diagnostic beam directed towards the patient during the treatment. The system further comprises a track that supports the diagnostic beam generator to move the diagnostic beam generator between one or more different positions so that the beam from each diagnostic beam generator is at a predetermined non-zero angle with respect to the beam of the diagnostic beam generator at a different position. The system further comprises one or more image recording device(s) located adjacent to the treatment bed for receiving the diagnostic beams from the diagnostic beam generator at the different positions in a sequential manner so that the image recording device captures the images from all of the diagnostic beams.
In accordance with yet another aspect of the invention, a method for treating a patient is provided wherein a three-dimensional mapping of a region of the patient including a target region to be treated by a treatment beam is utilized and one or more diagnostic beams directed towards the patient are generated. Then, one or more images are captured in one or more image recorder(s) when the diagnostic beams pass through the target region of the patient wherein the diagnostic beams pass through the patient at non-zero angles with respect to each other. Finally, the images from the diagnostic beams and the three-dimensional mapping are compared in order to control the movement of the treatment beam during the treatment.
To perform the comparison, the intra-treatment/live images are correlated to the pre-operation data as is well known. The pre-operative data provides spatial information on the relative placement of the anatomical structures from which the current intra-treatment position of the target region may be computed. To compute the target region position, the correlation method may comprise deforming the pre-operative data so that it optimally corresponds to the intra-treatment image data, or vice versa so that the deformation of the intra-treatment data better matches the pre-operative data.